General information

The climate(s) of Alaska

Climate observing stations

Climate data used for many of the analyses on this website are from National Weather Service first order observing stations and cooperative observing stations across Alaska, for which long term time series are available. Observations from the cooperative network are taken by dedicated volunteers in the community and provide a significant enhancement to the spatial coverage of climate data across Alaska.

Click on a station to see a description of the site.

Information courtesy of the National Climate Data Center.

Alaska Climate Regions

Zoom and click in map for more information on the climate regions:

Geography and climate

Because Alaska covers such a large area and has so many geographically distinct regions, there is no simple answer to the question: "What's the climate like in Alaska?" The main geographic variables that influence regional climate in Alaska are:

Latitude

Covering an area of 586,400 square miles and almost 20 degrees of latitude from about 51°N to 71°N, the spatial coverage of Alaska is quite expansive. Given the high latitude environment, the state experiences extreme seasonal variability in solar radiation. North of the Arctic Circle, areas experience constant daylight in the summer (often termed the Midnight Sun), but remain in darkness for much of the winter months. Because of the high latitude and the strong influence of sea ice on regional climate conditions, the North Slope experiences an Arctic climate rather than a typically maritime one even though it is relatively close to the ocean.

Continentality

With approximately 6,640 miles of coastline, a significant portion of Alaska is influenced by ocean waters and the seasonal distribution of sea ice. Locations that are under the predominant influence of the sea are characterized by relatively small seasonal temperature variability with high humidity. Conversely, locations that are inland and cut off from the moderating influence of the waters experience a continental climate. This type of climate is characterized by large daily and annual temperature range, low humidity and relatively light and irregular precipitation. In areas where the ocean freezes in winter, summer temperatures are similar to what is recorded in other maritime regions but it gets much colder in winter. The open ocean dampens seasonal temperature amplitudes due to the relatively higher specific heat capacity of water. When the water freezes and turns to sea ice this no longer applies.

Elevation

Alaska’s highest point is the summit of Denali at 20,310 feet (6190 m), just under four vertical miles above the state’s coastline. Altitude above sea level influences the climate of any given area. In the troposphere, the lower region of the atmosphere where most of our weather happens, temperature generally decreases with altitude above sea level. However, temperature inversions are frequent in winter in many regions of Alaska. In an inversion, the lowest few hundred feet of the atmosphere essentially decouple from the upper levels and radiative cooling causes a pool of cold air to form close to ground level. The cold air does not mix with the warmer air above it unless it is sufficiently disturbed by wind or precipitation. Inversions typically occur during calm, clear conditions and can be very persistent.

Elevation, and topography in general, also plays a significant role in the spatial variability of precipitation. Broadly speaking, precipitation increases with elevation. However, there are many small scale effects, especially in complex mountainous terrain, that can cause large differences in the amount of precipitation received locally.

It should be noted that the geographic factors latitude, continentality, and elevation are coupled. If one factor is changed and the other two remain constant, the relationship of that factor to climatological conditions is relatively straightforward. For example, at the same latitude and distance from the sea, it will be colder on a high mountain than in a valley, unless there is an inversion. However, low elevation regions in interior Alaska, such as the Yukon Flats and the Tanana Valley, often experience colder conditions than, e.g., higher elevation mountain regions on the Southeastern Coast due to their latitude and continentality.

Tourism is a major industry in Alaska, and an important part of enjoying a visit to our beautiful state is being prepared to deal with our widely-varying and ever-changing weather. In the following we provide an overview on Alaska weather and climate, as well as some general information for anyone new to Alaska. If you have further questions, you can contact us directly (LINK TO CONTACT FORM).

What to expect

Climatology does not attempt to predict the weather for your trip, rather show you what the historical averages are. A good approach to determine what type of weather to expect on your trip to Alaska is to look at the climatology of the location(s) you expect to visit. If you are a new visitor to Alaska, browse our station descriptions and climate regions section.

Climatology data should also be considered with a critical eye and all weather elements available should be taken into account. For example, let's say you are going to visit Juneau and Fairbanks in July. You will find that on average Juneau has 17 days with precipitation while Fairbanks has 12. You may then think that Juneau is only a little wetter then Fairbanks for this period. However, if you also consider the average precipitation in July you will see that Juneau has 4.16 inches of rain, and Fairbanks only 1.87 inches. Hence Juneau receives more than twice the rainfall in an average July than Fairbanks. The point of this is not to belittle either location’s weather, rather to make the lay person aware of the potential problems that can arise from mis- interpreting climatological data.

Many people will find it useful to compare the climatology data of their destination(s) with the data for, or near, their home town. This provides a basis of reference. For instance, you may find that summer in Fairbanks is like spring at your home. Then you would bring clothes you find comfortable for this type of weather.

The Golden Rule

There is one special rule that has been found to work for most travelers in Alaska, and that is to always be prepared for one season COLDER than the time you are travelling. This is especially important for those who travel early and late in the season. Likewise, if your plans are going to take you into any of Alaska's many mountainous regions, be prepared for cooler temperatures and higher winds.

Daylight

Alaska covers almost 20 degrees of latitude from about 51°N to 71°N. Because Alaska is located at such high latitudes and covers such a large area, there are strong variations in the amount of daylight we get over the course of a year and this also varies significantly depending on where in Alaska you are. North of the Arctic Circle, the sun never sets in summer, while winter is one long Arctic night. The further south you get, days are shorter in summer and longer in winter.

Twilight

Twilight occurs in the mornings and evenings when the sun is below the horizon but not so far that it is fully dark. The phase when the sun is between 0 and 6 degess below the horizon is refered to as "Civil Twilight". In the evenings this is followed by "Nautical Twilight" between 6 and 12 degrees, "Astronomical Twilight" between 12 and 18 degrees, and full night when the sun sinks below 18 degrees. In the mornings, the different twilight categories occur in reverse.

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